Background: The lungs and respiratory control mechanisms are not fully developed in infants born extremely prematurely, often necessitating high levels of supplemental oxygen (hyperoxia; HX) for survival. However, sustained use of HX impedes ongoing lung development and leads to the development of neonatal chronic lung disease (bronchopulmonary dysplasia; BPD). Improving respiratory control would reduce HX need and thus, BPD. However, the underlying mechanisms of dysfunctional breathing control remains unknown precluding therapeutic development. Pulmonary vagal sensory neurons may contribute to poor breathing in BPD. For example, pulmonary vagal sensory neurons (PSNs) marked by the expression of Neuropeptide Y receptor 2 (Npy2r) innervate the alveoli, which are damaged in BPD, and alter breathing when selectively stimulated. Given sensitization of other pulmonary vagal sensory neurons in other lung diseases, the objective of this study was to define the influence of Npy2r+ PSNs on breathing and if HX sensitizes Npy2r PSNs. Hypothesis: Stimulating Npy2r+ PSNs will inhibit breathing in healthy mice, an effect which will be magnified in BPD mice. Methods: Mice (M/F) were exposed to 90% O 2 for the first five days of life to induce BPD-like lung damage or room air as control (normoxia; NX). Lung tissue was collected in a subset of mice to verify BPD. For optogenetic studies, Npy2r-Cre driver mice crossed with Cre-dependent Ai32 mice produced offspring that express the light-sensitive protein ChR2 within Npy2r PSNs. At six to eight weeks of age, mice were anesthetized, the left cervical vagus exposed, and breathing recorded via spirometry before, during, and after repeated Npy2r PSN light stimulations. For conscious chemogenetic studies, NX and HX Npy2r-Cre driver mice were intratracheally treated with a Cre-dependent retrograde AAV to drive expression of the excitatory DREADD, hM3Dq (Gq). At four to six weeks of age, breathing was recorded via whole-body plethysmography before and after IP injection of the DREADD activator, DCZ. In situ hybridization confirmed Cre and ChR2 specificity within collected ganglion. Results: Mean linear intercept of HX lung tissue increased 128% compared to NX lung tissue, confirming alveolar simplification and BPD. Optogenetic stimulation of Npy2r+ PSNs decreased frequency (21%), tidal volume (70%), and minute ventilation (18%) in NX and HX Npy2rCre+Ai32 mice (percent change of baseline; n>7 per group). Without anesthetic influence, chemogenetic stimulation revealed that the 60% reduction in minute ventilation was driven by frequency in NX mice but tidal volume in HX mice (n>5 per group). Conclusion: These data suggest an inhibitory breathing role of Npy2r+ PSNs, and that HX alters the influence PSNs have on ventilatory control. Ongoing studies are testing the impact of Npy2r+ PSN inhibition in NX and HX mice. This work was supported by R01 NHLBI HL2215796. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Hennen et al. (Fri,) studied this question.